Tarandus
, , , , , | abbreviation = Tar | genitive = Tarandi | pronounce = Name: /'tər•an•dis/ Genitive: /'tər•an•dī/ | symbolism = the | mRA = | mdec= | ndec = | sdec = | wRA = | eRA = | quadrant = NQ4 | crossedby = Winter meridian | bordering = Avis (N) Hippocampus (E) Noctua (W/C) Simianus (SW) Solarium (SE) Testudo (E) | segments = 74 | area = 3882.439 sq. deg. (7 ) | proportion = 94.113‰ | average = 647.073 sq. deg. (3 ) | namedstars = 41 | figurestars = 4 | nakedeyestars = 315 | bfstars = 396 | brightstars = 17 | brighteststar = (0.77 }}) | nearbystars = 25 | neareststar = (1.83 , 5.98 ) | messierobjects = 27 | fullrange = 44°N–38°S | partialrange = 90°N–44°N 38°S–90°S | date = June 24 | astrosign = 11/23–12/22 | solarsign = 11/30–1/18 }} Tarandus is a caelregio located in the fourth quadrant of the at its midpoint, but it extends into the southern hemisphere and into the third quadrant. Tarandus is divided into six s (listed in the infobox), including , , and . Tarandus is located in the rich star fields because it points near the center of our galaxy. Because of this, this caelregio contains many examples of nebulae, star clusters, and star clouds but very few galaxies. Tarandus also contains the second nearest star system to Earth, which is the red dwarf , and is also the highest proper motion star known. Name and symbolism Tarandus was named after the , where it was located between and in the neighboring caelregio Testudo. Tarandus is named after the Latin word for . This caelregio can also be called Rangifer since it also means reindeer in Latin. It is imagined that reindeer, although a holiday creature, does share little relationship with (Aquila). Reindeer wears the (Scutum) for protection as worn by (Hercules), especially from arrows (Sagitta). Notable stars Bright stars An is the Tarandus' brightest star at a of 0.77, located in . Altair is one of the stars that make up the , the other two are and , both located in the neighboring caelregio Avis. The other notable bright stars in Tarandus are (a 1.80 located in Sagittarius), (a 2.08 A-type giant located in Ophiuchus), and (a 2.83 located in Sagittarius). Nearby stars is the Tarandus' nearest star at a of 5.98 s (1.83 s), located in Ophiuchus. It is also the second nearest star system overall after the system in Simianus. Barnard's Star is a with the highest known , moving at 10.3 arcsec/year. Barnard's Star can sometimes be referred as Proxima Ophiuchi. This star was discovered by the American astronomer in 1916. Barnard's Star was claimed to have planets but further observations find no evidence for planets. However, Barnard's Star is speculated to have three sub-Earth planets all orbiting within 0.105 . The innermost planet orbits only 0.008 AU from the star, taking 17 hours to orbit. Yet the planet's temperature is just 664 K (735°F, 390°C), cooler than and and it is a caused by the intense s from its parent star. Another notable nearby star is , which was claimed to have the first ever discovered in 1855, but subsequent observations gradually ruled out the planet's existence. However, 70 Oph is speculated to have eight planets, four orbit component A and four orbit component B. 70 Oph is a K-type main sequence star located 16.58 light-years away. Yet another nearby star speculated to have planets is , which is a K-type star speculated to contain nine planets, one more than in our . Variable stars The notable in Tarandus is (Alpha Herculis). This varies in brightness with a period between 50–150 days that is the result of irregular . Another variable star is . AM Her is the star also called . AM Her is a red dwarf varying between 12.3 and 15.7 magnitudes. Multiple stars is a , all are s. Star C is separated from the A-B pair by about 700 s, which itself separated by 4.6 arcseconds at minimum. 36 Ophiuchi speculatively contains eight planets, two around Star A, one around Star B, and five around Star C. Double stars The two stars of are separated by 0.46° which is more easily resolvable with the naked eye. ξ is nearly 5 times further away from the observer than ξ , 2069 vs. 365 light-years. Planetary systems As of 2015, there are nearly a hundred s identified orbiting more than 80 stars in Tarandus. A notable example is (P12 Tar) in Hercules, which has a Alpheus (HD 154345 b, P170). HD 154345 also contains six speculative planets, four of them are . Also in Hercules, (P15 Tar) has a long-period saturnian planet named Diomedes (HD 164922 b, P182) along with two speculative smaller planets closer to the star. (P1 Tar) has two long-period planets: Cerenytis (14 Her b, P20) and Eurystheus (14 Her c, P163). 14 Her also has two speculative planets orbiting closer than the two known planets: 14 Herculis d and 14 Herculis e. 14 Her e is in a 1:4 with Cerenytis while Cerenytis is in a 1:4 resonance with Eurystheus. So this puts three outer planets in a 1:4:16 , which would dynamically make 14 Herculis a very interesting planetary system. But the most famous example of a planetary system in Tarandus is (P35 Tar) in Ophiuchus, which has a super-Earth exoplanet detected by . This planet, named Shesha ( , P385), is a mini- with a hydrogen-helium atmosphere. Despite this planet has a relatively cool temperature of 516 K compared with all other transiting exoplanets, it has one of the closest orbits to the star than any other exoplanets. The planet's distance from the star is only the Earth–Sun distance and takes just 38 hours to orbit the star. The reason why this planet is so cool is because the parent star's radiation is only about as strong as the . Another star with a transiting planet is (P9 Tar, in Hercules), which has a planet named Augean ( , P151). Based on its density, the core makes up merely 70% the mass of this planet. The mass of this planet is 0.36 }} and the density 0.81 g/cm . Notable deep sky objects Tarandus contains a lot of notable deep sky objects. The ( 8, 6523), which is an , and , which is an , are located in Sagittarius. The (also known as the Swan Nebula, Horseshoe Nebula, Checkmark Nebula or the Lobster Nebula) (M17, NGC 6618) is an HII region also located in Sagittarius. Also in this constellation, there is , which is a at the center of . There is the (M24, 4715). This star cloud does contain the open cluster . Sagittarius also contains the nearest (NGC 6822, 57) located just 1.6 million light-years from the Milky Way. This galaxy is similar in structure and composition to the (SMC). The ( 2-9) is a located in Ophiuchus. Also in this constellation, there is the (NGC 6369). There is the (M13, NGC 6205), which is a bright visible to the naked eye in Hercules. contains the , which is a planetary nebula dotted with dense, bright knots of gas that resemble diamonds in a necklace. Ophiuchus contains two notable e: the ( 72) and . The Snake Nebula is a part of the much larger . B68 is also an and . The is a group of objects in Ophiuchus south of the star . It contains two globular clusters in the upper right, one reflection nebula from above to the upper left, and one dark nebula to the upper left in the image. This caelregio contains the ( 2151) of galaxies. This cluster contains about 100 galaxies, many are and . There is a globular cluster in Sagittarius: (also known as the Sagittarius Cluster) (NGC 6656), which is the first known globular cluster discovered in 1665 (possibly earlier). This globular cluster is the third brightest in the sky after and and before M13 just mentioned. This cluster is even more notable because it contains a planetary nebula. Sagittarius contains another globular cluster: (NGC 6809). This cluster appears more grainy than nebulous, which is more akin to an open cluster than a globular cluster. Sagittarius contains yet another globular cluster: (NGC 6681). This globular cluster is located close to the center of our galaxy and is visible through a small . This constellation contains yet another globular cluster: (NGC 6715), which was the first globular cluster found outside of our galaxy belonging to the . However this cluster was previously thought to belong to our galaxy until 1994 after it was discovered by in 1778. In , there is the (M11, NGC 6705), which is one of the densest s containing at least 3000 stars within a 23 light-year diameter. Ophiuchus contains Kepler's located in our galaxy after the progenitor star exploded in 1604. This supernova was seen by . It was the first naked-eye supernova since 1572 and the next naked-eye supernova would not take place until 1987. In Sagittarius, there is a rare example of triple appearing like a bird: the (also dubbed 'The Bird'). This triplet is composed of two massive and an . In Ophiuchus, there is the (NGC 6240), which is a remnant of a merger between two smaller galaxies and is a nearby . Gallery Visibility In the northern hemisphere, Tarandus can be visible from late fall till mid winter. Since the area of Tarandus is extremely similar between northern and southern hemispheres, observers at the and would see about equal proportions of Tarandus. The north pole observer would find that the northern half of Tarandus appears to circumnavigate clockwise along the horizon, and the southern half would never rise. The south pole observer would see that the southern half of Tarandus appears to circumnavigate counterclockwise along the horizon, and the northern half would never rise. Sagittarius contains the "Teapot" which the main stars make up the prominent arrow we see in the sky. Zodiac The appears to cross Tarandus from November 30 till February 15: it crosses the constellations Ophiuchus (November 30 till December 17), Sagittarius (December 18 till January 18), and then Capricornus (January 19 till February 15). This al caelregio is located between Simianus to the west and Hippocampus to the east. Tarandus was formerly in the from November 23 till January 20. Category:Articles Category:Caelregios